The invention relates to a forced mixer for producing mixtures from liquid, powdery and granular components, such as concrete mixtures.
A mixer of this type is known from DE 31 10 437 A. The outer mixing tool is formed as a worm gear which is imparted a revolving motion in a circular fashion along the mixer container wall. The inner and outer mixing screws convey in a upward direction.
It is an object of the invention to provide a mixer of the type described above which is particularly suited as a concrete mixer.
This object is achieved by a forced mixer characterised in that the outer mixing tool comprises mixing shares or mixing scrapers gliding along the mixer container surface contacted by the mixed material. While the screw of the inner mixing tool conveys the material in an upward direction, the shares or scrapers move the material in a substantially horizontal direction. As a result, it flows down more rapidly and complete intermixing takes place without any dead regions in the entire mixing container.
The centrally moving screw mixing tool feeds the mixed material in a vertical direction. As a result, the screw-conveyed mixed material is imparted a rotational motion. The outer mixing arm mixing tool counteracts this rotational motion. Due to these flows of mixed material crossing each other, a strong turbulence of the entire mixer contents and rapid and intensive intermixing are achieved.
As a further advantage of the forced mixer according to the invention, an outlet hopper is no longer needed since the mixing space may correspond to the conventional outlet hopper where a rubber hose, for example for filling a truck mixer, may be fixed using a flange. The screw mixing tool reaches all the way to the immediate vicinity of the slider arranged at the end of the outlet hopper in order to avoid non-mixed regions within the mixer.
Further embodiments of the invention are described in the dependent claims.